In the context of computers (e.g., desktops and laptops), computational functions are typically performed by a central processing unit (CPU), such as an Intel processor. Each CPU has a clock rate, which is the fundamental rate in cycles per second (measured in hertz) at which the CPU performs its most basic operations such as adding two numbers or transferring a value from one processor register to another. Different chips on a motherboard may have different clock rates. Usually when referring to a computer, the term “clock rate” is used to refer to the speed of the CPU. The first commercial PC, the Altair (by MITS), used an Intel 8080 CPU with a clock rate of 2 MHz. The original IBM PC (c. 1981) had a clock rate of 4.77 MHz (4,770,000 cycles/second). In 1995, Intel's Pentium chip ran at 100 MHz (100 million cycles/second), and in 2002, an Intel Pentium 4 model was introduced as the first CPU with a clock rate of 3 GHz (three billion cycles/second).
As clock rates have increased, the heat generated by the CPU has increased. In other words, the need for heat dissipation increases with rising frequencies, e.g., clock rates. At first, heat sinks were thermally connected to the CPU to dissipate heat. As the need for heat dissipation has increased beyond the ability of heat sinks alone with the increase in clock rates, fans have been added as part of the cooling system for the CPU. By way of example, computers today will typically include a heat sink thermally coupled to a CPU and a fan coupled to the heat sink. Some computers will also include a fan mounted on the case of the system unit to further assist in cooling the interior of the system unit, including the CPU.
Fans, however, are a noise generator. As a CPU does not always operate at the rated clock rate, the amount of heat generated by the CPU varies, and the amount of cooling required also varies. As mentioned above, the heat generated by the CPU increases with the speed at which the CPU is operating. Thus, the greater the clock cycle at which the CPU is operating, the more cooling resources are used (e.g., fans), and the greater the operating noise. Normally, internal noise contributors are managed for noise reduction purposes on the basis of a predetermined fixed cap, with a degree of variation tied to the internal system state. Such management may take place either within the internal noise contributor itself or on a system level, i.e., on the motherboard or processor. Placement, however, impacts the sophistication of the management. Parameters relating to a current external environment of the system, however, are not taken into consideration. Another issue is often found in that while fan speeds can be reduced to lower the internal noise level, this concomitantly abets an increase in internal temperature, thus resulting in an oft undesirable tradeoff.
In view of the foregoing, a need has been recognized in connection with managing internal noise levels in a manner that reasonably takes into consideration a wider variety of parameters and factors that might affect a user's comfort level.